1. Field of the Invention
The present invention relates generally to a surgical electrode lead, and more specifically relates to a ring electrode for a pacing lead.
2. Description of the Prior Art
Though the ring electrode has many applications, the most prevalent is within one conducting path of a bipolar pacing lead. In the bipolar pacing lead, a first conductor terminates in a tip electrode at the distal end of the lead. A ring electrode is located a short distance proximal to the tip electrode and is connected to a second conductor of the bipolar pacing lead.
The problems experienced in fabricating and using the ring electrode are often practical ones. The earliest ring electrodes were welded to the corresponding conductor. Many leads fabricated today still use a welding technique. U.S. Pat. No. 3,348,548 issued to Chardack teaches welding of the ring electrode to the conductor. A problem with the weld technique is that the insulating sheath must be cut to permit electrical contact of the conductor and the ring electrode. If, as with present day leads, the conductor must be sealed from body fluids, the cuts must be sealed by molding or some other technique.
A second general technique for attachment of the ring electrode is via crimping. U.S. Pat. No. 3,769,984 issued to Muench teaches attachment of a ring electrode via crimp rings. As with the welding technique discussed above, the insulating sheath must be cut to permit contact between the conductor and the ring electrode. Muench teaches "dipping the material in a suitable adhesive material" to seal the cuts. Whereas this technique is usable, the sealing process represents an added step. The use of crimp rings is further complicated by the requirement to precisely position the conductor relative to the crimp ring.